Up until very recently I had never tried reading a graphic novel. I finally read one and really enjoyed it. The experience was very different from reading a novel composed entirely of words, but was enjoyable nonetheless. Graphic novels and Manga are just different ways to tell a story. They are still written, but they are also drawn. So do I consider reading these types of stories reading? Yes.
That being said, I can understand why you may not include graphic novels/manga in some reading contests and things because they are generally faster reads than other forms of novels or audibooks because all of the description we're used to being written is now depicted in picture form. So I can see why it may not always be categorized with other reading for certain reasons, but it's still reading. The written word is still being used to convey a story to a reader, it's just paired with a visual now.
I do think that novels generally hold more substance than graphic novels/manga, purely because there is so much that can be conveyed through word that I think sometimes is lost in visual representations. I know many people who think the exact opposite though, so it all depends on the person and their preferences.
This is a short, somewhat scattered post, but share with me your thoughts in the comments! Do you consider reading graphic novels/manga reading? Or would you call it something else? Do you think that they represent a different kind of storytelling? Let me know your thoughts below!